MIAMI (CBSMiami) – A mystery illness, according to Broward County officials, that sent students at a elementary school sick has been identified as a virus.

The Florida Department of Health in Broward County have identified the virus, that made many school members sick, as Norovirus.

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“After a thorough investigation of testing of stool specimens, it has been determined that the agent causing the gastroenteritis is Norovirus. The precautionary measures including thorough and frequent hand washing and keeping ill children at home are effective and should continue,” the notice sent by the Department of Health reads.

According to the notice, the district is continuing to work with the Health Department to clean and sanitize all classrooms and common areas. Crews had worked over the weekend to ensure a clean environment and students returned to class Monday.

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Last Friday, the Broward School Board sent a letter to parents stating that Manatee Bay Elementary staff has received “numerous reports of students experiencing signs and symptoms of vomiting, diarrhea, and fever.”

The school district told CBS4 News more than 300 kids were out of school with some kind of bug with flu-like symptoms.

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For more information on Norovirus, please visit http://www.cdc.gov/norovirus/.”